This invention relates to a stamp such as a postage stamp, fee stamp, etc., and more particularly relates to a postage stamp incorporating electronic article surveillance technology (EAS).
In today's environment where the processing of mailpieces must be extremely efficient, there is increased reliance by postal authorities on using automatic equipment for the handling and sorting of mailpieces to ensure they reach a final destination in a timely manner. One such automated device is called a facer canceller. The facer canceller checks the surfaces of the mailpiece to determine if a stamp or a postage indicia is present, and based on that determination sorts the mailpiece for subsequent processing. That is, if neither a postage indicia nor a stamp is detected, the mailpiece is typically sent to a bin for manual inspection. If an indicia is determined to exist on the mailpiece, the mailpiece is sent to a separate station for further processing. On the other hand, if a stamp is detected, the facer canceller typically cancels the stamp by imprinting a postage mark on the stamp. The purpose of the postage mark is to visibly alter the stamp so that it cannot be reused.
To make it possible for the facer canceller to detect the stamp and indicia, the ink used in the indicia is a fluorescent ink while the ink used in the stamp is a phosphorescent ink. The facer canceller has light emitters and detectors that are capable of illuminating, detecting, and distinguishing between the different inks used in the indicia and the stamp to accomplish the sorting and canceling operations discussed above. Currently, facer cancellers owned by the United States Postal Service are capable of processing approximately 360,000 mailpieces per hour.
While existing facer cancellers have greatly increased the throughput processing capability of mailpieces, a problem still exists relative to the canceling of stamps. Due to the high processing speed of the facer canceller and the fact that there is a certain degree of variation in the positioning of individual stamps on the mailpiece, it is not uncommon for the facer canceller to apply the postage mark solely on a portion of the mailpiece, thereby missing the stamp. Moreover, if the ink supply runs low in the facer canceller, a visibly discernible postage mark might not be imprinted on the stamp. In either of the above two situations, the unmarked or inadequately marked stamp could be used again without the postal service receiving a fee for its use.
Additionally, the inks used for the postmarks can be removed using suitable solvents so that these "washed" stamps can no longer be distinguished from unused stamps. Once again, this can lead to the reuse of a stamp without any revenue being generated for the postal service.
Furthermore, if a properly canceled stamp is reused, it is difficult for a machine to detect a postmark optically since it is necessary to distinguish the postmark from the printing on the postage stamp. This distinction can be very difficult because the postmark or usually only part of it can appear anywhere on the stamp, on the one hand, and a great number of postage stamps with a great variety of printed patterns are always in circulation, on the other hand.
In order to solve some of the above-mentioned problems, it has been proposed to put a marker, such as a fluorescent substance, into the adhesive layer of the stamp. The marker can be detected in a conventional manner to authenticate the validity of the stamp. Moreover, if the stamp is pulled from the mailpiece for reuse, the fluorescent substance is removed from the stamp with the adhesive layer such that when the stamp is reused the fluorescent substance is not detected, thereby permitting the identification of the reused stamp so that the mailpiece associated therewith can be sorted out for further appropriate action. The problem with this proposed solution is that the entire stamp together with the portion of the substrate it is bonded to could be cut from the mailpiece and reapplied by adhesive to another mailpiece without removing the fluorescent marker. The stamp could therefore be reused without detection.
Thus, what is needed is a postage stamp which can be applied to a mailpiece, can be detected with automated equipment to determine its authenticity, and which can effectively be canceled after its first use to allow for its identification with automated equipment upon any subsequent reuse.